But what you probably don't know--since the research was just published--is that team sports have the greatest impact on mental health. (No. 2? Cycling.)

The study is one the first of its kind, and easily the largest--1.2 million people participated--to analyze the effect of different types of exercise on overall mental health.

In general terms, physical activity performed in groups, like team sports or fitness classes, provides greater benefits than walking, running, or lifting weights. (I'm kinda bummed about the last one. Wait....)

To determine the rankings you'll see below, researchers surveyed respondents to ask how many days in the previous month their mental health was "not good" due to depression, stress, or "problems with emotions."

The following list shows how people reported feeling after a month of different activities, compared to people who were not physically active. (The result indicates the percentage of fewer poor mental health days; for example, those participating in team sports reported 22.3 percent fewer bad days than those who did not exercise.)

Team sports: 22.3 percent

Cycling: 21.6 percent

Aerobic or gym exercise: 20.1 percent (does not include indoor bikes or treadmills)

Running or jogging: 19 percent

Recreational sports: 18.9 percent

Winter or water sports: 18 percent

Walking: 17.7 percent

Household chores: 11.8 percent

Obviously any form of exercise--even vacuuming--improves your mental health. Plenty of studies have proven that link. And the differences between the different forms of exercise are relatively small.

Keep in mind the link between exercise and mental health is correlated, not causal. Poor mental health may cause people to exercise less; better mental health may cause people to exercise more. (When I feel down, I'm a lot less likely to exercise.)

But then again, if I feel down and go for a ride...I always feel better. Exercise has a way of clearing my head, lifting my mood...I always feel better about myself, if only because of the inner pride that comes from doing something hard.

So maybe the link between better mental health and exercise is at least somewhat causal.

As Dr. Adam Chekroud, the senior author of the study, says:

"This is very strong evidence that there is a relationship between exercise and mental health. It seems like there are some sweet spots, and the relationship is probably complex. But even things like walking or household chores seem to have benefits."

Improve your health and fitness and improve your mental health at the same time?